The present invention relates to a signal output circuit of a push-pull type, and more particularly to a data output circuit employed in a semiconductor memory equipped with multistage sense amplifiers.
A signal output circuit of a push-pull type comprises first and second transistors connected in series between power supply terminals. The connection point of the first and second transistors is connected to a signal output terminal. True and complementary data signals to be outputted are supplied to the first and second transistors in such a manner that these transistors attain a push-pull operation. In a steady condition, one of the first and second transistors is a nonconducting state, and hence no penetrating current flows between the power supply terminals.
However, in response to change in a logic level of the data signals, one of the first and second transistors is brought from a nonconducting state to a conducting state, whereas the other of them is brought from a conducting state to a nonconducting state. In other words, both of the first and second transistors are made conducting at a transition time when the data signal changes its logic level, so that a penetrating current flows between the power terminals. The current ability of the first and second transistors is designed to be large to obtain a sufficient load driving capability. For this reason, the penetrating current is considerably large.
Such a large penetrating current increases a power consumption and further supplies a large noise signal to a signal processing section due to the impedance in power supply lines, thereby causing a misoperation and/or a data destruction.